Yes, and furthermore its the complete ignorance of how technology works that could lead to someone imagining that Redis could be a faster LRU than a `new ConcurrentHashSplayTree<String>()` in a single-process Java server (or equiv).
Apart from all the subtlety of not throwing away evicted lines until the last mail that uses them is discarded and such.
How can people think that mailnator is slow because its not using web 2.0 sauce?
Code cost of migrating to something external when thats worth it? About a connect string...